The present invention relates to a gear mechanism in a timepiece for preventing reverse rotation of a gear wheel.
In commonly used conventional means for prevention of reverse rotation of a gear wheel, a spring piece is provided for elastically contacting a gear wheel. In other conventional mechanisms, teeth of two gear wheels are shaped into special forms so that the gear wheels may bite each other when they turn in reverse direction. However, the latter gear mechanisms for preventing reverse rotation are defective in that it is very difficult to manufacture the gears since the teeth of the driving gear and the follower gear should be formed precisely. Moreover the distance between two gear shafts should be set accurately. The gear mechanism has further defects in that when the gear wheels bite each other, preventing reverse rotation, normal rotation starts require additional forces for releasing the bite state. As described above, the conventional gear mechanism requires accuracy in manufacturing, and has little practical effect considering the high cost of manufacturing.